Beavis,

I am assuming you are in the US, and from the sticky posting at the top of the MTB forum, there are plenty of options at $500 over there.

My advice is (if you are on a limited budget) get a quality hardtail rather than a used duallie.

Cheaper duallies (that you will now find at $500 used) are not built to be ridden a lot or hard. As a result, you take the risk of buying one that is stuffed, or buying something that is quickly stuffed.

Trickle down technology means you can get bikes now for $500 that would easily outperform what I was racing on as a sponsored rider in the mid 90s!

A quality hardtail at $500 will always be better value than a duallie at $750! Go Norco, Specialised or Kona and you can't go too far wrong.

If you don't have brand envy - get a Giant - they are usually great value for money.